The invention relates to an arrangement for open-end spinning having a twisting element, a yarn withdrawal nozzle, a yarn withdrawal device and a deflection arranged behind the yarn withdrawal nozzle in yarn withdrawal direction. The deflection has at least one false-twisting edge.
In the case of open-end spinning and particularly in the case of open-end rotor spinning in which a spinning rotor is used as the twisting element, the problem arises that the true yarn twist does not completely enter into the forming yarn. In the case of open-end rotor spinning, the true twist is applied essentially between a yarn withdrawal nozzle and a yarn withdrawal device that enters into the yarn piece partially upstream from the withdrawal nozzle, i.e., into the yarn piece extending from the yarn withdrawal nozzle to the rotor groove. Under certain circumstances, this yarn piece may therefore have less twist than normal yarn so that the spinning stability suffers, particularly when a yarn with a low twist is to be spun. In practice, the yarn withdrawal nozzles are usually provided with a surface structure so that due to the friction of the yarn at the yarn withdrawal nozzle, an increased false twist is to be generated such that the twist is increased in the yarn section between the yarn withdrawal nozzle and the rotor groove.
In order to introduce the true yarn twist into the yarn section located upstream from the yarn withdrawal nozzle to a more extensive degree, it is known (DE-OS No. 33 32 498) to arrange a deflection having at least one false-twisting edge in the area behind the withdrawal nozzle. This deflection has an inclination directed toward the moving direction of the yarn that extends approximately in the same direction as the inclination of the twist of the yarn resting against this false twisting edge. By this measure, an improved introduction of twist into the yarn section located in front of the yarn withdrawal nozzle is made possible.
An object of the invention is to develop an arrangement for a spinning unit such that the introduction of the true yarn twist into the yarn section located in front of the yarn withdrawal nozzle is improved.
This object is achieved by providing a deflection downstream from the yarn withdrawal nozzle in yarn withdrawal direction. Further, an additional deflection is provided that deflects the yarn into a direction that deviates from the direction of the preceding deflection.
By this measure, the effect of the at least one false-twisting edge is increased because the yarn is prevented to a more extensive degree from lifting itself of the at least one false-twisting edge and having the twist "skip over" this false-twisting edge. Further, by this second deflection, the moving path of the yarn is not significantly limited, so that it remains possible to suck a yarn end back into the spinning rotor for the purpose of piecing.
It is known (DE-OS No. 27 02 733) to let the yarn move via two deflecting edges acting in opposite directions, at a distance from a yarn withdrawal nozzle. The deflecting edges are directed transversely to the moving direction and serve the purpose of forming a type of twist block. However, it was found that in practice the effect of deflecting edges of this type, that extend transversely to the yarn moving path, does not result in an improvement of the distribution of the twist.
In further advantageous features of a preferred embodiment of the invention, it is provided that the two deflections are arranged on opposite sides with respect to the yarn. In a particularly advantageous way, it is further provided in this case that the deflection that is located on the outlet side contains at least one false-twisting edge. If the yarn lifts off the at least one first false-twisting edge, the effect of this edge is promoted because the yarn is subjected to the effect of the at least one second false-twisting edge to an increased degree so that the distribution of the twist is maintained.
In further advantageous features of a preferred embodiment of the invention, it is provided that the deflection downstream from the yarn withdrawal nozzle is formed by an insert that is inserted between two sections of a yarn withdrawal channel. In a further advantageous feature, it is also provided that the end of the second section of the yarn withdrawal channel that faces the insert is developed as a deflecting edge and/or a false-twisting edge.
In further advantageous features of a preferred embodiment of the invention, it is provided that a yarn withdrawal channel is connected to the yarn withdrawal nozzle. The yarn withdrawal channel is formed of two sections that are staggered with respect to one another. An insert contains the first and the second deflection and is arranged between the sections. In a further advantageous feature, it is provided that the insert is developed as a sleeve. The end of the sleeve facing the yarn withdrawal nozzle is developed as a false-twisting edge forming the first deflection, and the end facing away is developed as a false-twisting edge forming the second deflection. In this feature, only one insert is used in order to obtain both deflections.
In further advantageous features of a preferred embodiment of the invention, it is provided that a yarn withdrawal channel formed of two sections connects to the yarn withdrawal nozzle. An insert deflecting the yarn is arranged between the sections, and the insert is provided with at least one false-twisting edge. In this embodiment, three deflections are provided, including one at the end of the first section of the yarn withdrawal channel, one in the area of the insert and one at the start of the second section of the yarn withdrawal channel. This embodiment also has the advantage that the moving direction of the yarn is unchanged upstream from and downstream from the deflections. This allows an existing assembly to be modified.
In further advantageous features of a preferred embodiment of the invention, it is provided that a yarn withdrawal channel, that is formed of two sections that are staggered with respect to one another, is connected to the yarn withdrawal nozzle. Between the sections, two inserts are arranged that are provided with false twisting edges. The inserts provide a path of the yarn which is approximately S-shaped. The sections of the yarn withdrawal channel are connected approximately tangentially to the inserts.
In further advantageous features of a preferred embodiment of the invention, it is provided that an insert that forms an approximately sinusoidally shaped channel, is connected to the yarn withdrawal nozzle. Also, the insert is provided with at least one false-twisting edge in the area of the turning points. In this embodiment, it is advantageously provided that the insert includes two parts that form the channel between them.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.